1. Field of the Invention
The present invention relates to an image forming method; and a color filter, a spacer for liquid crystal display, and a projection for orientation control, which are formed by the image forming method. More specifically, the invention is an image forming method used suitably by liquid crystal display devices for reflection and transmission displays; and a color filter, a spacer for liquid crystal displays, and a projection for orientation control, which are formed by the image forming method.
2. Description of the Related Art
A color filter is used in a color face plate for cathode ray tube displays, a photoelectric conversion element plate for copying, a filter for single-tube system color television cameras, a flat panel display using liquid crystal, a color solid state image pickup device, or the like. A conventionally used color filter is made by regularly arranging the three primary colors (blue, green and red). A color filter having four or more hues as required is also known.
In recent years, as a liquid crystal display (LCD), a reflection type liquid crystal display device has been developed for a portable terminal, a typical example of which is a portable telephone. However, a problem of a reduction in display quality in rooms and dark places has been noticed. As a measure for improving the display quality, reflection and transmission dual purpose liquid crystal display devices have been suggested.
An example of the reflection and transmission dual purpose structure of the liquid crystal display device, includes an embodiment illustrated in FIG. 3. In this embodiment, reflective layers 12, which may be referred to as reflective plates, are arranged at predetermined intervals in a light transmittable substrate 10B, and transparent layers 16 are arranged at predetermined intervals in a light transmittable substrate 10A. Pixels 14 are formed to cover a part of each of the transparent layers 16. The light transmittable substrates 10A and 10B are set to be opposite to each other, and a liquid crystal layer 18 is formed therebetween.
In the case of a transmission display, the display is attained by transmitted light a from a backlight 20. In the case of a reflection display, the display is attained by reflected light c obtained by external light b being transmitted through the light transmittable substrate 10A and reflected by the reflective layers 12.
In the case of the reflection and transmission dual purpose display, the thickness of the portion of the color filter, through which portion light is transmitted, is the same for the transmission portion and the reflection portion. In the case that sufficient brightness is realized for reflection display, the color purity of the transmission portion is insufficient. In the case that the color purity of the transmission portion is conversely made sufficient, an inconvenience, wherein the reflection portion becomes dark, is caused. In order to solve such problems, making the thicknesses or hues of the transmission portion and the reflection portion of the color filter different from each other, so as to improve display quality, has been tried. However, this process is complicated and the costs rise.
To inclease the functions of an LCD panel, development of techniques for increasing the field angle, the contrast thereof and the like are progressing. Among those techniques, a VA technique, which uses a vertical orientation mode, and the formation of a spacer using a photo spacer are becoming mainstream. These mainstream techniques require a photolithography step for fabricating a structure of the spacer, and a photolithography step for fabricating a structure of a projection for orientation control, which is essential for the VA technique. Thus, costs of the LCD panel rise.